Heat the butter in a large pot over medium heat. Saute the shallots until opaque, a few minutes. Add the parsley, wine, pepper, sea salt and lemon juice. Turn the heat up to high and bring the mixture to a boil. Let reduce for 3 minutes. Add the mussels, cover and shake the pot every minute so that the mussels cook evenly. When the mussels open, they're done. Discard any unopened ones.
Toast the bread, rub with the garlic clove and spread with butter. Spoon 6 to 8 mussels into each bowl and add 2 slices of bread.